Irrigation of large areas such as golf courses, parks and the like is a complicated matter. Typically, automatic equipment is utilized in which a plurality of sprinkler stations are strategically located throughout the area to be irrigated. Each sprinkler station contains a valve for controlling the flow of water entering the station from a source of pressurized water and exiting the station to a sprinkler line terminating in a plurality of sprinkler heads. The sprinkler heads are located at preselected locations so as to water the lawns, trees and shrubbery in a thorough and efficient manner. The various sprinkler stations are electrically connected back to a common controller. Since the water required by lawns, trees and shrubbery differs, it is usual to operate the sprinkler stations associated with lawn areas from one sprinkler station and those areas associated with shrubberies and trees from a separate and distinct sprinkler station. The controller to which the sprinkler stations are all ultimately connected is a clock operated device with the capability of keeping track of both the hours of the day and the day of the week. The clock mechanisms contained in such controllers operate switches which open and close the circuits to the various sprinkler stations so as to accomplish the irrigation of the area in an optimum manner.
Previously developed irrigation sprinkler system controllers have implemented their functions in a mechanical manner. Mechanical clock mechanisms drive one or more controller wheels having pins, cams and the like mounted thereon which operate the sprinkler station switches. The controller wheels of such devices are typically marked with the parameter being controlled such as the time of day or day of week. The activation pins, cams or the like are movable by the operator so as to "program" the controller to operate in the desired manner.
With only a few sprinkler stations to be controlled and under steady conditions, such mechanical controllers have provided a fairly workable system. However, as the number of stations to be controlled becomes large, the mechanical controllers have become excessive in size with compounding of mechanical failures. These mechanical failures are due to contact corrosion and limited duty cycles, as well as wear in the operation or changing of operating times or the like due to movement of mechanical parts. Such mechanical controllers may also present a problem to the operator for reprogramming or modifying an existing program.
Many of the disadvantages associated with mechanical irrigation controllers have been minimized through the use of automated programmable solid state controllers. Such irrigation controllers are described in U.S. Pat. No. 4,165,532 issued to Kendall, et al. on Aug. 21, 1979 and entitled "Automatic Irrigation Sprinkler System Controller" and U.S. Pat. No. 4,189,776 issued to Kendall on Feb. 19, 1979 and entitled "Simplified Irrigation Controller". Such controllers have provided increased reliability and simplification in the programming of the controller. Typically, input keyboards and the logic sequences incorporated therein are adapted to provide the operator with a wide selection of features. Start times, run times and programming calendars are directly input as alpha-numeric data through the keyboard which incorporates a plurality of numerically associated keys for the input of such data.
Such solid state logic controllers, however, do present problems to the average home owner when desiring to program his controller. The keyboard entry system for programming the controller in which dual functions may be associated with a single key of the keyboard and the associated entry sequence presents the home owner with a "computer" type looking irrigation controller which both physically and psychologically present a deterrent to its use.
A need has thus arisen for an irrigation controller which utilizes the state of the art microprocessor solid state logic and control circuitry to provide a reliable controller yet one which includes a simplified data entry system for operator use in programing and reprogramming the controller.